“…The modern achievements of the theory of the stability of the critical positions of equilibrium of ordinary differential equations include the establishment of the criteria of stability for model systems with a codimension of at most three inclusive, the establishment of the algebraic insolvability of the problem of the stability in the critical case [12], the study of the stability in resonance cases [12], the Molchanov's solution of the problem of the stability in the critical case of n pairs of purely imaginary roots in the absence of resonances [12,16], the study of the critical states of equilibrium of nonautonomous ordinary differential equations [20] and difference equations [10], the study of the critical positions of equilibrium of impulsive differential equations [5,8], and the proof of the semialgebraic solvability of the problem of the stability for monotone differential equations [15,17].…”